Dragon Slayers: Remastering and Redefining the Enduring Struggle

This paper uses a historical perspective to examine the lasting appeal of a particular fairy tale throughout a variety of cultures and time periods. By analyzing the various interpretations of characters within the dragon slayer tale type, we can see the cultural significance of fairy tales throughout history. It examines similarities and differences between three examples of the tale type (Perseus and Andromeda from 8 AD in Greece and Rome, The Saga of Ragnar Lodbrok from the 13th Century in Northern Europe, and The Two Brothers from 1857 in Germany), taking into account the differing perspectives and life experiences of readers and listeners to each of these tales and how it might contribute to their ability to relate to the plot and characters, as well as the lessons they might take away from the stories

The Impact of Fiber-Reinforced Polymer Constructions on Risk Level onboard Large Passenger Ships

The main objective of this project was to determine how a FRP composite structure performs compared to a steel structure in regard to fire safety and risk level during an evacuation. More specifically the objective was to study how the differences in the thermal properties influence the smoke layer height, visibility and the temperature of the gases in the early stages of a fire. This was done by performing several FDS simulations and analyzing the results from these. In order to evaluate the difference in risk level, the time until critical conditions occurred was compared between the FRP and steel cases. The results showed small differences in time until critical conditions for the smoke layer height and visibility while the temperatures also showed only slight differences near the fire but larger differences further away and as time went by. This led to the conclusions that there is a difference in risk level based on the reasoning that time until critical conditions further away also matter. However, additional research is needed in order to determine if the difference is significant or not.Fiberförstärkta plastkonstruktioners inverkan på risknivå ombord på stora passagerarfartyg Användning av fiberförstärkta plastkonstruktioner (FRP) inom den marina sektorn har blivit alltmer intressant ur ett hållbarhetsperspektiv. Problemet med FRP som byggnadsmaterial är att det är brännbart, vilket på grund av tradition och reglering gör det svårt att övergå från, det mer traditionella materialet stål, till FRP. Därför måste det bevisas att materialet är säkert ur flera olika aspekter. En av dessa är säkerheten vid utrymning av passagerare. Genom användning av lättare konstruktionsmaterial såsom kompositmaterial av fiberförstärkt plast (FRP) kan den totala vikten av ett skepp minskas. En minskad vikt medför också en minskad bränsleförbrukning eller att tyngre last kan transporteras med samma bränsleförbrukning som tidigare. Därmed är denna fråga aktuell eftersom den kan medföra ekonomiska fördelar för skeppsägare och hela den marina transportsektorn. Inte att förglömma är även en minskad miljöpåverkan eftersom den minskade bränsleförbrukningen leder till mindre utsläpp. Detta låter så klart jättebra, så varför har skeppstillverkare inte börjat använda lättviktsmaterial i större utsträckning än? Jo, det är förstås också viktigt att bevisa att användningen av materialen inte medför negativa effekter. Det kan vara effekter såsom att skeppskonstruktionen inte klarar av att bära upp större belastning än vanligt, eller att personer som utrymmer vid brand påverkas negativt mer på grund av att materialvalet påverkar hur brandens förlopp ser ut. Byggnadsmaterialet FRP har helt andra egenskaper jämfört med stål. Det väger endast en femtedel så mycket och mjuknar vid mycket lägre temperaturer. Materialet är dessutom brännbart till skillnad från stål. Dessa faktorer är exempel på sådant som måste tas hänsyn till vilket betyder att det måste vidtas åtgärder för att se till att materialet är lika säkert som stål. Tidigare projekt har visat att en ökad värmeisolering av materialet bidrar till att materialet klarar av högre temperaturer samt att materialet inte börjar brinna. Det beror på att temperaturökningen som sker i samband med branden inte direkt påverkar materialet utan istället måste ta sig igenom själva isoleringen innan materialet kan börja värmas upp eller antändas. Dock är det så att en ökad mängd isolering gör att brändernas förlopp blir snabbare och större, vilket medför att det eventuellt kan vara så att personers säkerhet vid brand påverkas negativt. Målet med det utförda examensarbetet var att undersöka om den ökade mängden isolering som används i FRP-konstruktioner har några negativa effekter på risken under utrymningsförloppet. Detta gjordes genom att jämföra hur en kompositkonstruktion av FRP påverkar förhållandena för utrymning jämfört med en stålkonstruktion. De parametrar som studerades var tider till kritiska förhållanden för brandgaslagerhöjd, siktbarhet och brandgasernas temperatur. Tid till kritiska förhållanden innebär tiden från dess att branden startar tills tiden då det uppstår förhållanden som inte är godtagbara enligt boverkets föreskrifter. Jämförelsen gjordes genom att utföra CFD-simuleringar i programmet FDS där en likadan geometri användes men där varje fall simulerades för både en FRP-konstruktion och en stålkonstruktion. Allt detta gjordes genom FDS-simuleringar av en enkel korridorsgeometri med passagerarkabiner på vardera sidor och fokus låg på att observera eventuella skillnader i utrymningsparametrarna i det tidiga brandförloppet, alltså vid den tid när utrymning kan antas ske. Resultaten visade att det var små skillnader i tider till kritiska förhållanden för brandgaslagerhöjden och siktbarheten. Temperaturerna visade små skillnader i tider till kritiska förhållanden nära branden, men ökande skillnader i tiderna längre bort från branden och längre in i brandförloppet. Slutsatsen som kundes dras i examensarbetet är att det finns en viss skillnad i risknivå när man använder FRP jämfört med stål, vilket motiverades med att även förhållanden längre bort från brandkällan påverkar utrymningssäkerheten. Dock ansågs det viktigt att påpeka att denna slutsats grundar sig på ett antal simuleringar och en enda geometri, vilket leder till att det krävs ytterligare forskning för att ta reda på om dessa skillnader också uppnås vid andra sorters bränder, testmetoder och geometrier. Författare: Anders Lynnér och Josip Novacic. Titel examensarbete: The Impact of Fiber-Reinforced Polymer Constructions on Risk Level onboard Large Passenger Ship

Skeletal correlates for body mass estimation in modern and fossil flying birds.

Scaling relationships between skeletal dimensions and body mass in extant birds are often used to estimate body mass in fossil crown-group birds, as well as in stem-group avialans. However, useful statistical measurements for constraining the precision and accuracy of fossil mass estimates are rarely provided, which prevents the quantification of robust upper and lower bound body mass estimates for fossils. Here, we generate thirteen body mass correlations and associated measures of statistical robustness using a sample of 863 extant flying birds. By providing robust body mass regressions with upper- and lower-bound prediction intervals for individual skeletal elements, we address the longstanding problem of body mass estimation for highly fragmentary fossil birds. We demonstrate that the most precise proxy for estimating body mass in the overall dataset, measured both as coefficient determination of ordinary least squares regression and percent prediction error, is the maximum diameter of the coracoid's humeral articulation facet (the glenoid). We further demonstrate that this result is consistent among the majority of investigated avian orders (10 out of 18). As a result, we suggest that, in the majority of cases, this proxy may provide the most accurate estimates of body mass for volant fossil birds. Additionally, by presenting statistical measurements of body mass prediction error for thirteen different body mass regressions, this study provides a much-needed quantitative framework for the accurate estimation of body mass and associated ecological correlates in fossil birds. The application of these regressions will enhance the precision and robustness of many mass-based inferences in future paleornithological studies

Mantle dynamics of the Andean Subduction Zone from continent-scale teleseismic S-wave tomography

The Andean Subduction Zone is one of the longest continuous subduction zones on Earth. The relative simplicity of the two-plate system has makes it an ideal natural laboratory to study the dynamics in subduction zones. We measure teleseismic S and SKS traveltime residuals at >1000 seismic stations that have been deployed across South America over the last 30 yr to produce a finite-frequency teleseismic S-wave tomography model of the mantle beneath the Andean Subduction Zone related to the Nazca Plate, spanning from ~5°N to 45°S and from depths of ~130 to 1200 km. Within our model, the subducted Nazca slab is imaged as a fast velocity seismic anomaly. The geometry and amplitude of the Nazca slab anomaly varies along the margin while the slab anomaly continues into the lower mantle along the entirety of the subduction margin. Beneath northern Brazil, the Nazca slab appears to stagnate at ~1000 km depth and extend eastward subhorizontally for >2000 km. South of 25°S the slab anomaly in the lower mantle extends offshore of eastern Argentina, hence we do not image if a similar stagnation occurs. We image several distinct features surrounding the slab including two vertically oriented slow seismic velocity anomalies: one beneath the Peruvian flat slab and the other beneath the Paraná Basin of Brazil. The presence of the latter anomaly directly adjacent to the stagnant Nazca slab suggests that the plume, known as the Paraná Plume, may be a focused upwelling formed in response to slab stagnation in the lower mantle. Additionally, we image a high amplitude fast seismic velocity anomaly beneath the Chile trench at the latitude of the Sierras Pampeanas which extends from ~400 to ~1000 km depth. This anomaly may be the remnants of an older, detached slab, however its relationship with the Nazca-South America subduction zone remains enigmatic.Fil: Rodríguez, Emily E.. University of Arizona; Estados UnidosFil: Portner, Daniel Evan. No especifíca;Fil: Beck, Susan L.. University of Arizona; Estados UnidosFil: Rocha, Marcelo P.. Universidade do Brasília; BrasilFil: Bianchi, Marcelo B.. Universidade de Sao Paulo; BrasilFil: Assumpção, Marcelo. Universidade de Sao Paulo; BrasilFil: Ruiz, Mario. Escuela Politécnica Nacional; EcuadorFil: Alvarado, Patricia Monica. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geofísica y Astronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Centro de Investigaciones de la Geosfera y Biosfera. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones de la Geosfera y Biosfera; ArgentinaFil: Condori, Cristobal. Universidade do Brasília; BrasilFil: Lynner, Colton. University Of Delaware; Estados Unido

In-situ measurement of texture development rate in CaIrO₃ post-perovskite

The rate of crystallographic preferred orientation (CPO) development during deformation of post-perovskite is crucial in interpreting seismic anisotropy in the lowermost mantle but the stability field of MgSiO3 post-perovskite prevents high-strain deformation experiments being performed on it. Therefore, to constrain the rate of CPO development in post-perovskite, we deformed CaIrO3, a low-pressure analogue of MgSiO3 post-perovskite, in simple shear at 3.2GPa and 400○C to a shear strain (γ) of 0.81. From X-ray diffraction patterns acquired during deformation, we invert for CPO as a function of strain. By comparing the CPO that develops with visco-plastic self-consistent (VPSC) models we constrain the critical resolved shear stresses (CRSS) of the non-primary slip-systems in CaIrO3 to be of order 6 times stronger than the primary [100](010) slip system. This value is significantly less than has been assumed by previous studies and if applicable to MgSiO3 implies that seismic anisotropy in the D′ layer develops slower than has previously been assumed

Triggered crustal earthquake swarm across subduction segment boundary after the 2016 Pedernales, Ecuador megathrust earthquake

Megathrust ruptures and the ensuing postseismic deformation cause stress changes that may induce seismicity on upper plate crustal faults far from the coseismic rupture area. In this study, we analyze seismic swarms that occurred in the north Ecuador area of Esmeraldas, beginning two months after the 2016 M$_{w}$ 7.8 Pedernales, Ecuador megathrust earthquake. The Esmeraldas region is 70 km from the Pedernales rupture area in a separate segment of the subduction zone. We characterize the Esmeraldas sequence, relocating the events using manual arrival time picks and a local a-priori 3D velocity model. The earthquake locations from the Esmeraldas sequence outline an upper plate fault or shear zone. The sequence contains one major swarm and several smaller swarms. Moment tensor solutions of several events include normal and strike-slip motion and non-double-couple components. During the main swarm, earthquake hypocenters increase in distance from the first event over time, at a rate of a few hundred meters per day, consistent with fluid diffusion. Events with similar waveforms occur within the sequence, and a transient is seen in time series of nearby GPS stations concurrent with the seismicity. The events with similar waveforms and the transient in GPS time series suggest that slow aseismic slip took place along a crustal normal fault during the sequence. Coulomb stress calculations show a positive Coulomb stress change in the Esmeraldas region, consistent with seismicity being triggered by the Pedernales mainshock and large aftershocks. The characteristics of the seismicity indicate that postseismic deformation involving fluid flow and slow slip activated upper plate faults in the Esmeraldas area. These findings suggest the need for further investigation into the seismic hazard potential of shallow upper plate faults and the potential for megathrust earthquakes to trigger slow-slip and shallow seismicity across separate segments of subduction zones

Structural Control on Megathrust Rupture and Slip Behavior: Insights From the 2016 Mw 7.8 Pedernales Ecuador Earthquake

The heterogeneous seafloor topography of the Nazca Plate as it enters the Ecuador subduction zone provides an opportunity to document the influence of seafloor roughness on slip behavior and megathrust rupture. The 2016 M$_{w}$ 7.8 Pedernales Ecuador earthquake was followed by a rich and active postseismic sequence. An internationally coordinated rapid response effort installed a temporary seismic network to densify coastal stations of the permanent Ecuadorian national seismic network. A combination of 82 onshore short and intermediate period and broadband seismic stations and six ocean bottom seismometers recorded the postseismic Pedernales sequence for over a year after the mainshock. A robust earthquake catalog combined with calibrated relocations for a subset of magnitude ≥4 earthquakes shows pronounced spatial and temporal clustering. A range of slip behavior accommodates postseismic deformation including earthquakes, slow slip events, and earthquake swarms. Models of plate coupling and the consistency of earthquake clustering and slip behavior through multiple seismic cycles reveal a segmented subduction zone primarily controlled by subducted seafloor topography, accreted terranes, and inherited structure. The 2016 Pedernales mainshock triggered moderate to strong earthquakes (5 ≤ M ≤ 7) and earthquake swarms north of the mainshock rupture close to the epicenter of the 1906M$_{w}$ 8.8 earthquake and in the segment of the subduction zone that ruptured in 1958 in a M$_{w}$ 7.7 earthquake

Internal deformation of the subducted Nazca slab inferred from seismic anisotropy

Within oceanic lithosphere a fossilized fabric is often preserved originating from the time of plate formation. Such fabric is thought to form at the mid-ocean ridge when olivine crystals align with the direction of plate spreading1, 2. It is unclear, however, whether this fossil fabric is preserved within slabs during subduction or overprinted by subduction-induced deformation. The alignment of olivine crystals, such as within fossil fabrics, can generate anisotropy that is sensed by passing seismic waves. Seismic anisotropy is therefore a useful tool for investigating the dynamics of subduction zones, but it has so far proved difficult to observe the anisotropic properties of the subducted slab itself. Here we analyse seismic anisotropy in the subducted Nazca slab beneath Peru and find that the fast direction of seismic wave propagation aligns with the contours of the slab. We use numerical modelling to simulate the olivine fabric created at the mid-ocean ridge, but find it is inconsistent with our observations of seismic anisotropy in the subducted Nazca slab. Instead we find that an orientation of the olivine crystal fast axes aligned parallel to the strike of the slab provides the best fit, consistent with along-strike extension induced by flattening of the slab during subduction (A. Kumar et al., manuscript in preparation). We conclude that the fossil fabric has been overprinted during subduction and that the Nazca slab must therefore be sufficiently weak to undergo internal deformation

1D-velocity structure and seismotectonics of the Ecuadorian margin inferred from the 2016 Mw7.8 Pedernales aftershock sequence

International audienceOn April 16th 2016 a Mw 7.8 earthquake ruptured the central coastal segment of the Ecuadorian subduction zone. Shortly after the earthquake, the Instituto Geofisico de la Escuela Politecnica Nacional of Ecuador, together with several international institutions deployed a dense, temporary seismic network to accurately categorize the post-seismic aftershock sequence. Instrumentation included short-period and broadband sensors, along with Ocean Bottom Seismometers. This deployment complemented the permanent Ecuadorian seismic network and recorded the developing aftershock sequence for a period of one year following the main-shock. A subset of 345 events with ML > 3.5, were manually picked in the period of May to August 2016, providing highly accurate P- and S-onset times. From this catalogue, a high-quality dataset of 227 events, with an azimuthal gap <200°, are simultaneously inverted for, obtaining the minimum 1D velocity model for the rupture region, along with hypocentral locations and station corrections. We observe an average Vp/Vs of 1.82 throughout the study region, with relatively higher Vp/Vs values of 1.95 and 2.18 observed for the shallowest layers down to 7.5 km. The high relative Vp/Vs ratio (1.93) of the deeper section, between 30 km and 40 km, is attributed to dehydration and serpentinization processes. For the relocated seismicity distribution, clusters of events align perpendicular to the trench, and crustal seismicity is also evidenced, along with earthquakes located close to the trench axis. We also compute Regional Moment Tensors to analyze the different sources of seismicity after the mainshock. Aside from thrust events related to the subduction process, normal and strike-slip mechanisms are detected. We suggest that the presence of subducting seamounts coming from the Carnegie Ridge act as erosional agents, helping to create a scenario which promotes locking and allows seismicity to extend up to the trench, along zones of weakness activated after large earthquakes